THE DICOTYLEDONES 



1721 



Good King Henry) is cultivated for its leaves under the name of Mercury, 

 while Spinacia oleracea is the Garden Spinach. 



The plants are mostly annual or perennial herbs, occasionally shrubs or 

 very rarely small trees. Many as we have seen above are halophytes, and 

 as a result their anatomy has been considerably modified. Hairs are 

 commonly developed and their shape and form is made use of in separating 

 certain genera and species. In Chetiopodiiim, Salsola and Atriplex these 

 hairs are of peculiar structure, each consisting of a short stalk, bearing a 

 large thin-walled end cell containing a clear watery sap. These terminal 

 bladders easily collapse and form a peculiar mealy covering. They serve 

 to store water at an early stage in the development of the plant but lose their 

 contents when the structure on which they are borne reaches a certain age, 

 afterwards acting as a protective covering. 



In Chenopodiiim and Atriplex (Fig. 1595) the leaves are large and often 

 hastate, but in many members of the family the leaves are greatly reduced 

 and mav be narrow and cylindrical in section. 

 In Salicornia (F^ig. 1596) the stems are appar- 

 ently leafless, each internode ending in a narrow 

 cuplike ring embracing the base of the one 

 above. The internal anatomy shows clearly the 

 outer cortex of these stem joints is foliar in origin 

 and is derived from a decurrent development of 

 the cuplike leaf-sheath of the pair of leaves at 

 the node above. 



A watery storage system of large cells con- 

 taining sodium chloride and other mineral salts 

 in solution is common in halophytic C.henopodi- 

 aceae. In dorsiventral leaves these cells occupy 

 the upper and lower surfaces with the green 

 pahsade tissue lying in a layer between or even 

 in some cases concentrated around the vascular 

 bundles. In centric leaves, e.g., Salsola, this 

 water-storage tissue forms the bulk of the leaf 

 while the assimilatory cells form a zone beneath 

 the epidermis. 



The inflorescence is frequently of a mixed 

 type; racemes, panicles and spikes of small 

 cymes are all common. 



The flowers are hermaphrodite, monoecious or actinomorphic and, 

 except in Beta, hypogynous, with the parts arranged in fives. They are 

 generally much reduced. 



The perianth may consist of five sepals which are persistent after 

 flowering. They may be united at their bases. Five sepals are present in 

 the genera Chenopodiiim, Beta (Fig. 1597), Salsola and Suaeda: three or 

 sometimes four in Salicornia, while in the female flowers of Atriplex there 

 are only two. 



Fig. 1596. — Salicornia stiicta. 

 Entire plant. 



